Messages in this thread | | | Date | Tue, 21 May 2013 09:21:40 +0200 | From | Borislav Petkov <> | Subject | Re: NOHZ: WARNING: at arch/x86/kernel/smp.c:123 native_smp_send_reschedule, round 2 |
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On Tue, May 21, 2013 at 10:20:51AM +0800, Michael Wang wrote: > This is not enough to prove that policy->cpus is wrong, the cpu could > be online when get from policy->cpus, but offline when checked here, > since hotplug is able to happen during the period.
Strictly speaking you're correct but I don't do any hotplug besides the one-time thing which is part of halting the box.
> I don't get it... > > get_online_cpus() is just stop hotplug happen after it was invoked, so > unless policy->cpus is really wrong, otherwise all the cpu it masked > won't go offline any more.
Yes, that's my impression too - at the point we do gov_queue_work, policy->cpus already contains offline cpus.
> This protect nothing...before we go here, the cpu could already > offline, nothing changed...
Yes, but I don't want to schedule work on an offlined cpu and that is ensured here.
> If you really want to confirm the policy->cpus was wrong, the way > should be apply the fix I suggested, than check online in here.
Sure, feel free to get a box, enable NO_HZ_FULL and do all the experimentations you desire. I surely cannot be the only one who triggers this.
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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